1. Field of The Invention
The present invention relates to an overload prevention device for a film winding/rewinding motor for a camera and, more, particularly to an overload prevention device for a film winding/rewinding motor for a camera which can prevent a breakage of the camera and the teeth of a film advance gear by preventing an overload of a winding motor rotated in state that a one comma switch (a comma switch is defined as a switch for transferring one frame of the film in the camera herein) is not turned OFF when finishing a photograph, and by controlling an operation of the motor.
2. Description of the Prior Art
Generally, a motor is operated in accordance with a three comma switch when a film is charged in a camera, and three frames of the film are transferred, so that a winding/rewinding motor for transferring the film of a high quality camera enters a standby mode to take the photograph. The winding motor is operated in accordance with the operation of a one comma switch if after each photograph is finished, the film is automatically transferred. When the roll of film is fully used the motor is rotated by a separate circuit in a reverse direction and the exposed film is rewound.
However, less than one frame of film is transferred in case of the transfer of the frame of the film when the photograph is finished, and in a predetermined time interval, all frames of the film are rewound. At this time, since less than one frames of film was transferred in the case of the last one frame of the film and a remaining part of the last frame of the film was not transferred, the one comma switch remains in the ON state. AS the result, the winding motor is continuously rotated and an overload occurs. The overload is sensed by a circuit and the rotation of the motor is controlled.
The device for sensing the overload of the motor and stopping the operation of the motor is embodied, as well known, by an electrical circuit. Conventionally, when the film comes to the last frame of the film, the one comma switch is turned ON, the motor is rotated and all the frames of the photographed film are rewound.
Accordingly, in case of the film photographed in accordance with the operation of the motor, the motor is continuously rotated since the one comma switch is continuously turned ON in the state that less than one frame of the film is transferred.
An overload occurs to the motor when it is continuously rotated in a state when the film is not transferred. To prevent the overload of the motor, it is common to use a capacitor that is charged to an overcharged state. When this occurs a high level is applied to a base terminal of a transistor, the motor is turned OFF, the rotation of the motor stops and at the same time, all the frames of the film photographed completely will have been rewound by the operation of the rewinding circuit.
However, if the circuit malfunctions, the overload of the motor can not be prevented in advance, which causes breakdown. Also, it is very difficult to fix the camera when it is broken and the repair cost may not be justified for middle and low class cameras. As a result, there is a problem in that the camera can not satisfy the purchasers.